Cao Dawei, Ataya Mohamad, Chen Zhangpei, Zeng Huiying, Peng Yong, Khaliullin Rustam Z, Li Chao-Jun
Department of Chemistry, and FRQNT Centre for Green Chemistry and Catalysis, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A 0B8, Canada.
Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology and Electron Microscopy Centre, Lanzhou University, 730000, Lanzhou, P. R. China.
Nat Commun. 2022 Apr 4;13(1):1805. doi: 10.1038/s41467-022-29327-z.
The cleavage and formation of carbon-carbon bonds have emerged as powerful tools for structural modifications in organic synthesis. Although transition-metal-catalyzed decarbonylation of unstrained diaryl ketones provides a viable protocol to construct biaryl structures, the use of expensive catalyst and high temperature (>140 C) have greatly limited their universal applicability. Moreover, the direct activation of two inert C - C bonds in diaryl ketones without the assistance of metal catalyst has been a great challenge due to the inherent stability of C - C bonds (nonpolar, thermo-dynamically stable, and kinetically inert). Here we report an efficient light-driven transition-metal-free strategy for decarbonylation of unstrained diaryl ketones to construct biaryl compounds through dual inert C - C bonds cleavage. This reaction featured mild reaction conditions, easy-to-handle reactants and reagents, and excellent functional groups tolerance. The mechanistic investigation and DFT calculation suggest that this strategy proceeds through the formation of dioxy radical intermediate via a single-electron-transfer (SET) process between photo-excited diaryl ketone and DBU mediated by DMSO, followed by removal of CO to construct biaryl compounds.
碳-碳键的断裂与形成已成为有机合成中用于结构修饰的有力工具。尽管过渡金属催化的无张力二芳基酮脱羰反应为构建联芳基结构提供了一种可行的方法，但昂贵的催化剂和高温（>140℃）的使用极大地限制了它们的广泛适用性。此外，由于碳-碳键固有的稳定性（非极性、热力学稳定且动力学惰性），在没有金属催化剂辅助的情况下直接活化二芳基酮中的两个惰性碳-碳键一直是一项巨大的挑战。在此，我们报道了一种高效的光驱动无过渡金属策略，用于无张力二芳基酮的脱羰反应，通过双惰性碳-碳键断裂构建联芳基化合物。该反应具有反应条件温和、反应物和试剂易于操作以及对官能团耐受性优异的特点。机理研究和密度泛函理论计算表明，该策略通过光激发的二芳基酮与由二甲基亚砜介导的1,8-二氮杂二环[5.4.0]十一碳-7-烯（DBU）之间的单电子转移（SET）过程形成二氧自由基中间体，随后去除一氧化碳以构建联芳基化合物。
